The present invention relates to a magnetic bearing for rapidly rotating machines, in particular, for turbo compressors, drag vacuum pumps, or similar, comprising two bearings, each with a stator magnetic-ring set and a rotor magnetic-ring set and means for damping the rotor movement.
U.S. Pat. No. 5,059,092 shows a magnetic bearing of this kind consisting of two bearings. The first, passively designed bearing has engaging stator and rotor magnetic rings. The second, actively designed bearing is equipped with two rotor magnetic rings spaced axially apart. In the ring chamber formed by these rings, a ring disk made of non-magnetizable material with good electrical conducting properties, effects the desired damping, in particular for the radially directed movements of the rotor. This damping is based on the induction of eddy currents by changing the magnetic flux in the electrically well conducting material. The eddy currents generated by the disk by perpendicularly penetrating magnetic fields generate electromagnetic counteracting forces opposing the radial deflections of the rotor system, thereby damping these movements.
One disadvantage of the magnetic bearing of U.S. Pat. No. 5,059,092 is that both the magnetic rings of the passive bearing as well as the magnetic rings and the ring disk located in between, engage. Thus, assembly is complicated. Moreover, changes in the length of the rotor which occur due to temperature loads give rise to bearing problems. Moreover, damping is restricted to the location of the active bearing, meaning that the counteracting forces effecting the damping action are present only locally.
It is the task of the present invention to create a magnetic bearing having the characteristics detailed above, in which the damping action is not restricted to one of the two bearings, and in addition to render manufacture and assembly more simple.
In that the damping means can be assigned to each of the magnetic rings, preferably assigned at least to a part of the magnetic rings of the magnetic-ring sets each on the stator side, counteracting forces can be generated in both magnetic bearings damping the rotor movement, i.e. not only in the actively controlled bearing. Engaging of rings on the stator and the rotor sides is not required.
One advantage is that, compared to the prior art, manufacture and assembly of the bearings is more simple.